Radiology
Localized form (Predominantly hyline vascular subtype) :
Plain film typically reveals a sharply marginated mass with smooth or lobulated borders within the mediastinum or hila. On unenhanced CT, the masses are typically homogeneous, but they can also appear heterogeneous. Following contrast administration there is generally marked homogeneous contrast enhancement of the mass (the plasma cell variant may not enhance to the same degree). Lesions have a tendency to lie on one side of the midline or over the hilum. The lesion may have poorly defined margins and invade contiguous structures. Calcification is uncommon (5-10%)- typically punctate or coarse, discrete, and central.
MR imaging has been performed in a small number of cases and typically demonstrates heterogeneous signal intensity higher than skeletal muscle on T1 images and marked hyperintensity on T2 images. Peripheral foci of decreased signal correspond to vascular flow voids. The lesions enhance after the administration of gadolinium.
On angiography, the masses in the hyaline vascular subtype show a prolonged dense tumor blush in the capillary phase. Pre-operative embolization has been used to decrease intra-operative bleeding.
Mulicentric variant (Predominantly plasma cell type) :
There is typically no dominant mass. Multiple, enhancing nodes may be seen in the chest, axilla, retroperitoneum, mesentery, and inguinal regions. Splenomegaly and ascites may also be seen in these cases. Thin section CT findings include the presence of poorly defined centrilobular nodules, thin-walled cysts, and interlobular septal thickening. These findings are felt to be related to an associated lymphocytic interstitial pneumonitis.
|
|
